METHOD OF REINFORCING MASONRY

Abstract: A method of reinforcing masonry such as a brick wall which comprises forming a slot (16) in the wall, locating a reinforcing wire (15) in the slot (16) and embedding the wire (15) in grout (17). The grout (17) is injected into the slot (16) through a nozzle (11) which is moved progressively along the slot (16) as injection continues. The grout (17) is ejected towards the rear of the slot (16) from an outlet (12) in the trailing edge of the nozzle (11). In an alternative embodiment, the wire is threaded through a hole in the nozzle.

Description: METHOD OF REINFORCING MASONRY The present invention relates to the reinforcement of masonry. It is suitable for all forms of masonry materials including bricks, blocks, concrete, stone etc. and is applicable not only to walls and other vertical members but also horizontal and inclined members and surfaces. It is however particularly applicable to brick walls and will be described with reference to brick walls though it will be understood that the invention is not limited to this particular application. It is known for wires to be built into walls of masonry and unreinforced concrete in order to repair cracks which have developed in them as a result of movements, often of the ground beneath, due to subsidence or earthquakes, for example. This provides additional strength and the capacity to span openings beneath. In some situations, a continuous beam may be formed with top and bottom bands of reinforcement some distance apart. A strong girder- beam of this kind can redistribute loads from unstable to more stable ground. EP-A-171250 and GB-A-2249120 describe systems of reinforcement where slots are cut in existing walls and non-corrosive wires or rods are embedded in the slots using grout. The method of grouting wires into the slots envisaged in GB-A-2249120 has involved first injecting grout into the back of a slot, then pressing in a wire and injecting grout in front of it and pressing in another wire, if more than one is needed, and injecting grout in front of this one also; so that each wire is fully surrounded with grout which fills up the whole of the slot . One object of the present invention is to provide simpler and more reliable ways of embedding wires so that they are fully surrounded in the grouting material, and correctly positioned within it, and with fewer separate operations. According to the invention, there is provided a method of reinforcing masonry which comprises forming a slot in the masonry surface, locating a reinforcing wire in the slot and applying grout to the slot, so that the grout is injected into the slot through a nozzle which is moved progressively along the slot as injection continues; the grout being ejected towards or at the rear of the slot from an outlet in the trailing edge of the nozzle. The slot may be cut in an existing wall or may be formed in a new wall as it is constructed, for example by locating a filler at the front of a mortar layer between two courses of brick. When a slot is cut in a brick wall, it is conveniently cut into an existing mortar layer. The slot may be of any size but would typically have a thickness (top to bottom in a vertical wall) of 8mm to 16mm, preferably corresponding with the thickness of a mortar bed in that wall, and a depth (front to rear) of 20mm to 70mm, preferably extending at least up to the middle third of the thickness of the wall. In certain circumstances, the slot could extend almost through the entire wall thickness. The reinforcing wire may be in the form of a bar or rod and may have any suitable profile. A preferred form of wire is a helically-twisted, preferably stainless steel, wire as described in EP-A-171250. The wire should be non-corrosive and is preferably of metal. There may be two or more wires and these may be overlapped to form a continuous line of reinforcement. The grout may be any suitable grouting material and may be for example cement- based or resin-based. The nozzle is suitably dimensioned to fit into the slot. The leading edge may be thickened or strengthened to improve wear-life. The outlet in the nozzle is preferably oblique to its intended progressive direction of travel, so that the grout would tend to exude to the rear both in terms of the direction of travel and in relation to the depth of the slot and then exude outwards of the slot. The opening preferably extends to the end of the nozzle, thereby potentially reaching the rear of the slot in use. In one embodiment, the nozzle is relatively flat and is adapted to pass over the wire(s) in the slot . There might be a tendency for the wires to be pushed outwards by the grout as it exudes outwards from the rear of the slot. Thus, the wire(s) may be kept in position in the slot by some means on the nozzle such as guides protruding from the lower surface of the nozzle. Alternatively, spacers may be located in the slots which hold the wire(s) . Such spacers would preferably not extend above the top of the wires, in order to avoid obstructing passage of the nozzle. Where the wires are to be pre-tensioned prior to grouting-in, there may be no necessity for any guiding function. In a second embodiment, the nozzle may have one or more openings through which the wires may be threaded. This would serve to ensure the correct positioning of the wire(s) in the slot as the grout tends to exude outwards. Preferably the openings would be located in the leading edge of the nozzle only; in use, the wires would extend out through the rearwardly-facing nozzle outlet. Preferably, the grout is subjected to a certain degree of pressure upon leaving the nozzle. This serves to ensure that air is expelled and the grout soundly encapsulates the wire or wires. It also tends to cause liquid adsorption at the brick surface, thereby aiding the setting of the grout, and helps to ensure that any holes or indentations in the bricks are filled. The pressure may be achieved partially by back-pressure from the previously injected grout and partially by the design of the nozzle. Newly injected grout may be constrained at the wall surface by a pressure member or pointing arm, or the nozzle itself may define a cavity in which the grout is pressurised around the wire(s) . At all events, the grout is preferably effectively constrained within an enclosure as it encapsulates the wire(s) . Air would normally be expelled from the slot by the grout outwards of the slot and forwards past the nozzle. In use, an operator can judge whether or not the grout is being injected satisfactorily by the state of the grout to the rear of the nozzle. The speed of progression along the slot and the injection pressure can be adjusted intuitively to provide a smooth, void-free grout which does not protrude out from the wall. It has been found that the method of the invention results in higher speeds and better quality control for the reinforcement operation. Furthermore, the operation is simpler and less costly than existing techniques. The invention also extends to the nozzles themselves. The invention may be carried into practice in various ways, and certain embodiments will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a nozzle for use in accordance with a first embodiment of the invention; Figure 2 is a different perspective view of the embodiment of Figure 1 in use with a plurality of wires; Figure 3 shows a guide suitable for use in conjunction with the first embodiment; Figure 4 is a perspective view of a nozzle for use in accordance with a second embodiment of the invention using a single wire; Figure 5 is a different perspective view of the second embodiment, modified for use with two wires; Figure 6 is a perspective view of a third embodiment of the invention; and Figure 7 shows a wall with reinforcements located in accordance with the invention. Figure 1 shows an injection nozzle 11 which is generally flat and has an outlet opening 12. The outlet 12 is angled obliquely and faces towards what will be the trailing edge in use. An arm 13 also extends in the trailing direction while a guide plate 14 and hand grip 18 are provided at the leading edge. The leading edge of the nozzle 11 (in this and other embodiments) may be thickened to improve wear life. In use, a reinforcing wire 15 is located in a slot 16 cut in a wall and the nozzle 11 is connected to a pressurised source (not shown) of grout. The nozzle is located in the slot 16 above the wire 15 and grout 17 is injected into the slot 16 towards the rear. The nozzle 11 is moved along the slot 16 progressively and the grout 17 exudes over the wire 15 and towards the front of the slot 16. By maintaining a certain back-pressure, the operator ensures that the wire is fully embedded or encapsulated and any air is expelled forwards and outwards. The arm 13 irons in the grout 17 at the trailing edge and helps to maintain the back-pressure. The guide plate 14 is pressed against the wall surface to ensure the nozzle 11 is correctly positioned in the slot 16. Figure 2 illustrates a similar operation but in this case there are two wires 15, 15' side by side. One of the wires 15' is shown overlapped at 21 to provide continuous reinforcement over a significant length. The arrow A shows the direction of progressive movement of the nozzle 11 while the arrows B show the path taken by the grout. In order to keep the wires 15, 15' in position as the grout 17 is injected, a spacer 22 may be used as shown in Figure 3. This spacer 22 is of plastics material and has two channels 23 which receive the wires 15, IS'. The spacer 22 does not protrude above the wires 15, 15'. It is dimensioned so that its rear edge 24 abuts the rear of the slot 16 while the front edge serves to check that the slot 16 is the correct depth. Figure 4 shows an alternative form of nozzle 41 for use in a second embodiment of the invention. Again, a single wire 15 is located in a slot 16. The nozzle 41 has an outlet 42, an arm 43, a guide plate 44 and a hand grip 48 in the same way as the nozzle 11. However, the nozzle 41 is thicker or less flat and its leading edge has a hole 45 through which the wire 15 is threaded, the wire 15 passing out through the outlet 42. In use, the operation is very similar to that described in relation to Figures 1 and 2. However, the grant 17 will clearly be encapsulating the wire 15 within the outlet 42 of the nozzle 41. Figure 5 shows a nozzle 51 designed to embed a pair of wires 15, 15'. It has two holes 55, 56 in its leading edge but is otherwise similar to the nozzle 41, and is used in a similar fashion. Figure 6 shows a nozzle 61 arranged to operate according to a third embodiment of the invention. The nozzle 61 has an inlet 62 arranged for connection to a pressurised source (not shown) of grout. It has holes 63 in its leading edge through which wires 15, 15' are threaded. There is a chamber 64 behind the leading edge connected to the inlet 62 and guide surfaces 65. A long generally rectangular tube 66 extends in the trailing direction from the chamber 64 terminating in an oblique outlet 67. In use, the wires 15, 15 are threaded through the holes 63 and out of the outlet 67. Those holes 63 not in use are stopped with plugs 68. The nozzle 61 is connected to the grout source and is located within a slot 16 with the guide surfaces 65 abutting the wall above and below the slot 16. Thus the chamber 64 and tube 66 are within the slot 16. The grout 17 is injected and the nozzle 61 is moved progressively along the slot 16. The grout 17 fully encapsulates the wires 15, 15' within the tube 66 and back pressure at the outlet 67 causes the grout 17 to exude into the clearances left by the tube 66 as it moves forwards. Since the outlet 67 extends from the rear to the front of the tube 66, there is no necessity for an arm to iron-in the grout 17. Figure 7 shows a girder beam which can be readily incorporated in slots formed in a previous unreinforced wall. Such beams may comprise reinforcement to provide a top chord 71, a bottom chord 72 and diagonal lattice type reinforcement 73. Such beams could be effectively continuous over variable ground supports, as in subsidence or earthquake regions.

Claims: CLAIMS 1. A method of reinforcing masonry which comprises forming a slot (16) in the masonry surface, locating a reinforcing wire (15) in the slot (16) and applying grout (17) to the slot, so that the grout (17) surrounds the wire (15) , characterised in that the grout (17) is injected into the slot (16) through a nozzle (11) which is moved progressively along the slot (16) as injection continues; the grout (17) being ejected towards or at the rear of the slot (16) from an outlet (12) in the trailing edge of the nozzle (11) . 2. A method as claimed in Claim 1, characterised in that the slot (16) is cut into an existing mortar layer in a brick wall. 3. A method as claimed in Claim 1 or Claim 2, characterised in that the slot (16) is 8 to 16mm thick and 20 to 70mm deep from front to rear. 4. A method as claimed in any preceding Claim, characterised in that the wire (15) is a helically twisted stainless steel rod. 5. A method as claimed in any preceding Claim, characterised in that a plurality of wires (15, 15') are located side by side in the slot (16) . 6. A method as claimed in any preceding Claim, characterised in that the grout (17) is a resin-based grout. 7. A method as claimed in any preceding Claim, characterised in that the outlet (12) in the nozzle is arranged obliquely to the progressive direction of travel whereby the grout (17) is caused to exude to the rear of the slot (16) . 8. A method as claimed in any preceding Claim, characterised in that the nozzle (11) is relatively flat and is passed over the wire (15) in the slot (16) . 9. A method as claimed in Claim 8, characterised in that the wire (15) is kept in position in the slot (16) by guides on the nozzle (11) or by spacers (22) located in the slot (16) . 10. A method as claimed in any preceding Claim, characterised in that the wire or wires (15, 15') are pretensioned prior to the injection of grout (17) . 11. A method as claimed in any of Claims 1 to 7, characterised in that the wire(s) (15, 15') are threaded through holes (45) in the nozzle (41) and the nozzle (41) is moved along the wire (15) as the grout (17) is injected into the slot (16) . 12. A method as claimed in any preceding Claim, characterised in that the grout (17) is subjected to pressure upon leaving the nozzle (11, 41, 61) . 13. A method as claimed in Claim 12, characterised in that the pressure is achieved at least in part by a pressure member (13) at the trailing edge of the nozzle (11, 41). 14. A method as claimed in Claim 11, characterised in that the, nozzle (61) defines a cavity (64, 66) within which the grout (17) is subjected to pressure as it surrounds the wire(s) (15, 15') passing through the nozzle (61) , immediately prior to the grout (17) passing out of the nozzle (61) .

Inventors: OLLIS WILLIAM HENRY, OLLIS WILLIAM JOHN BERNARD, OLLIS, WILLIAM, HENRY, OLLIS, WILLIAM, JOHN, BERNARD
Applicants: OLLIS WILLIAM HENRY, OLLIS WILLIAM JOHN BERNARD, OLLIS, WILLIAM, HENRY, OLLIS, WILLIAM, JOHN, BERNARD
Application year: 1994
Main classification: E04G23
IPC codes: E04F21, E04G23